The following abbreviations and terms are herewith defined:
AGaccess gatewayBSbase stationIPInternet protocolWi-FiWLAN based on the IEEE 802.11WiMAXworldwide interoperability for microwave access(IEEE 802.16)WLANwireless local area networkWMNwireless mesh networkWNOwireless node
A mesh network is defined by a number of physical nodes arranged with full mesh topology where each node is connected directly to each other node or with partial mesh topology where nodes are connected to only some, not all, of the other nodes. While the topology at a particular configuration at a particular time may be hierarchical, a mesh network is not so limited and the topology enables many-to-many connections. A mesh network is also capable of dynamically updating and optimizing these connections. A WMN may be (but does not have to be) a “mobile network” in which at least some of the nodes of the network are mobile units (e.g., end users) that change position over time. In this regard the mobile user equipments act as a part of the WMN itself. Other WMNs do not employ user equipments to route traffic and rely on network-dedicated nodes, which may be fixed or mobile (e.g., mounted to a train). WMNs may communicate in accordance with various communication standards such as Wi-Fi and WiMAX, as non-limiting examples.
Within a WMN, a system that has a direct connection to an IP backbone is termed a mesh BS or AG. Usually there is no direct link from user devices to the BS/AG and traffic is routed through one or more hops over the network nodes. At least for scheduling, some WMNs use centralized scheduling where the AG or mesh BS collects the control and data packet information to determine the resource assignment for each WNO (router) and ensures that transmissions are coordinated to ensure collision-free scheduling. Other WMNs use distributed scheduling where each WNO (router) performs independent scheduling while coordinating with their extended neighbors. These different scheduling strategies are relevant for how embodiments of the invention detailed herein might be implemented, either centralized such as at the AG or distributed in each node.
WMNs have been rapidly deployed as a community (and federated) access network both in the developed as well as in the emerging telecommunications markets. It is reported that nearly seventy percent (70%) of the world's population lives in rural areas of developing or underdeveloped regions. But providing power to the network is expected to be a key design and performance aspect. In emerging markets, electrical supply is sometimes intermittent, unreliable or even non-existent. A WMN in these areas may need to rely on alternative sources of energy (e.g., batteries, solar, etc.), which are expensive. Conserving power in those areas helps in reducing the investment in alternative sources of energy, which can be expensive. In the developed market, although the electrical supply is reliable, conserving power helps in reducing network's operational costs and meeting certain environmental objectives. So conserving power in the wireless mesh network (WMN) serves the twin purposes of minimizing both the capital and operational expenditures of WMNs. Embodiments of this invention is seen to help address the power constraints of a WMN in such emerging markets so as to enable a WMN to be established more readily and operated more reliably given the electrical power constraints, as well as to conserve the less scarce electrical power in established economies.
From a power consumption perspective, there is much research into conserving battery power of battery-powered user devices by operating the radio interface (e.g., the transceiver) at a reduced power mode at certain times. Some research has also gone into that field for the network nodes (see for example US Pat. Publication 2007/0066329 which describes a technique for moving between active and standby modes for a base station of a cellular-type network). But the wireless nodes consume power on the order of watts, and only a small fraction (on the order of milliwatts) of that is consumed by its radio interface. So the largest gains in power conservation occur by turning off the WNOs completely if certain conditions are met, and some representative conditions might be loss of power, battery's reserve capacity falling below a threshold, and/or link inactivity.
For the WMN scenario the connectivity of the users through the network is not well-defined as it is in a hierarchical network. Determining which WNOs, and in fact determining if any of the WNOs, can be shut down is therefore not a straightforward task. The inventors are unaware of any specific research made public that details a solution to this particular problem. What is needed in the art is a way to determine which WNOs are necessary for connectivity through the WMN so that at least some of the remaining WNOs can be shut down, which is seen as enabling the potential for significant power savings without disrupting the network functionality. It would be particularly advantageous if such a determination were dynamic, so that more WNOs would be shut down at conditions of low traffic (e.g., midnight to 5 AM) when fewer of the WNOs are necessary for connectivity and so that fewer (if any) of the WNOs would be shut down at conditions of peak traffic.